FRACKING REACHING AQUIFERS
According to NSI Technologies President Michael Smith, fracturing is typically conducted thousands of feet below aquifers and the chances of creating a flow path for natural gas to the surface are small. Well-construction problems and gas seepage from poor well completions close to the surface would be more likely culprits. If the well penetrates a large natural fault there is some risk, when pumping huge volume water fractures, that water can be injected at high pressure directly into the fault, causing a minor earthquake.
How fracking can connect to unplugged wells, underground faults, mines & gas pockets
The driller drills down thousands of feet until he reaches the gas bearing strata. When gas is hit, the driller tries to use muds etc. to prevent the gas from blowing up the hole. If there is an old orphaned unplugged well nearby that penetrates the same gas bearing strata and the fracking pressure reaches it, gas or fluids could rise up into shallower strata and cause problems.
Also, new fissures opened by pressurized fracking fluid can connect to unknown natural fissures, providing an unforeseen pathway for methane or chemicals to flow up to groundwater.
Where do the fractures go?
According to COGCC, they "stay in the formation of interest. Typical fracture: "half" length: 300' to 1500'. Height: 20' to 300'. Width: 0.1" to 1.3". Energy Force: less than -1 on Richter Scale"
The Garfield County Hydrogeologic Study in 2008 was among the first to broadly analyze the ability of methane and other contaminants to migrate underground in drilling areas, and to find that such contamination was in fact occurring.
The three-year study examined over 700 methane samples from 292 locations and found that methane, as well as wastewater from the drilling, was making its way into drinking water not as a result of a single accident but on a broader basis.
As the number of gas wells in the area increased from 200 to 1,300 in this decade, methane levels in nearby water wells increased too. The study found that natural faults and fractures exist in underground formations in Colorado, and that it may be possible for contaminants to travel through them.
"It challenges the view that natural gas, and the suite of hydrocarbons that exist around it, is isolated from water supplies by its extreme depth," said Judith Jordan, the oil and gas liaison for Garfield County. "It is highly unlikely that methane would have migrated through natural faults and fractures and coincidentally arrived in domestic wells at the same time oil and gas development started, after having been down there for over 65 million years."
STRONGER Colorado findings
The COGCC requires identification of potential conduits for fluid migration in some circumstances, for example, the requirement to identify plugged and abandoned wells with 1/4 mile of CBM [coalbed methane] wells and gas seeps and springs within two miles of such wells. The COGCC GIS map system has a layer that shows the bottomhole location, and the COGCC staff includes this information in their review of historic plugged and abandoned wells within 1/4 mile. Also, for horizontal wells, the COGCC adds permit conditions requiring pressure monitoring of all producing wells within 500 feet for a 24-hour period during hydraulic fracturing.
The COGCC should consider whether there are additional circumstances or expanded areas where operators should be required to identify and address potential conduits for fluid migration in the area of hydraulic fracturing.
How a Gas Well Is Drilled Down Into the Ground, and What Can Go Wrong
Hydraulic Fracturing in Colorado
How fracking is harmful
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